Cam follower arrangements may be used in a turret assembly of a machine arrangement to help change a position of a ram assembly, such as a push or die ram assembly, relative to a lateral axis of a shaft of the turret assembly. Specifically, the cam follower arrangement may include cam follower(s) that follow a cam of the turret assembly so that components (e.g. tooling, push plate) connected to the ram assembly may influence an article (e.g. can, container). Conventional cam follower arrangements have shorter life spans, e.g. 6000-8000 hours, resulting from the manner in which the cam follower(s) is mounted to the ram assembly.
One type of conventional cam follower arrangement includes a single cam follower rigidly mounted on a translating element or housing of the ram assembly. Motion of the translating element is controlled by the interaction between the cam follower and cam surfaces of a groove in the cam. A clearance exists between the cam follower diameter and the cam surfaces to allow the cam follower to rotate. Disadvantages result because undesirable skidding may occur between the cam follower and the cam surfaces due to a direction change in translation that causes a direction change in rotation. The undesirable skidding increases when the speed of the shaft increases. Such skidding decreases the life of the turret assembly because it results in unnecessary wear and tear on the cam follower and cam surfaces.
Another type of conventional cam follower arrangement includes two cam followers rigidly mounted on a translating element or housing of the ram assembly. Motion of the translating element is controlled by interaction between the cam followers and cam surfaces of a rib on the cam. The second type of conventional cam follower arrangement maintains a constant rotational direction, but a clearance exists between the cam follower and the cam surfaces to accommodate for variations in the cam follower diameter and rib thickness. Disadvantages result because undesirable skidding may occur due to a direction change in translation, thereby resulting in the cam followers going from not contacting the rib to contacting the rib. The skidding decreases the life of the turret assembly because it results in unnecessary wear and tear on the cam followers and cam surfaces.
Another type of conventional cam follower arrangement includes two cam followers where the first cam follower rigidly mounts to a translating element or housing of the ram assembly and the second cam follower mounts to a spring between the second cam follower and the translating element. Motion of the translating element is controlled by interaction between the two cam followers and the cam surfaces of a rib on the cam. No clearance exists in the third type of cam follower arrangement. Instead, a spring keeps the cam followers in constant contact with the cam surfaces by accommodating for variations in cam follower diameter and rib thickness. Disadvantages may result because the spring creates a large spring force to counteract the forces created by the acceleration imparted to the translating element by the cam surfaces. For example, the spring force may be between about 150-200 lbf. The spring force depends on the dimensional variations within tolerance ranges. The spring force is affected by the shape of the cam surfaces and the mass of the translating element, thereby exerting an unnecessary average force on the cam followers and the cam surfaces. The unnecessary force may wear down the cam followers and cam surfaces, thereby reducing the life of the turret assembly.